1. Field of the Invention
The present invention relates to a stage device for positioning a wafer to be processed or the like in, for example, a semiconductor exposure apparatus, and an exposure apparatus using the stage device, and a method for producing a device.
2. Description of the Related Art
In exposure apparatuses used for producing semiconductors, accurate and quick positioning of, for example, a wafer to be exposed is required. Accordingly, progress is being made in the development of an XY stage (stage device) such as a wafer stage in which a linear motor, serving as a driving section, permits accurate positioning of the wafer and has excellent responsivity.
FIG. 10 is a view showing a general reduction projection type exposure apparatus comprising such components as a wafer stage (XY stage) E used for positioning a wafer W, a projection optical system A disposed thereabove, a reticle stage B, and a light source optical system C. Exposure light from the light source optical system C passes through a reticle on the reticle stage B in order to form an image thereof on the wafer W by means of the projection optical system A, whereby the reticle pattern is transferred onto the wafer W.
The wafer stage E is disposed above a table 110 in order to support the projection optical system A and the reticle stage B, with the body frame D being raised from the table 110. Vibration removal devices H are provided between a base G which supports the table 110 and the floor surface F.
The vibration removal devices H, which flexibly support the table 110, serve to prevent transmission of outside vibration to the wafer stage E and the body frame D.
The position of the wafer stage E is measured using a laser interferometer J, and the measured position is fed back to a control system of the wafer stage E. The light source optical system C is supported by a light source support K which rises directly from a floor surface F.
As shown in FIG. 9, the wafer stage E is an XY stage comprising a Y stage 120 capable of freely reciprocating above the table 110 in the Y-axis direction, an X stage 130 capable of freely reciprocating with respect to the Y stage 120 in the X-axis direction, a pair of Y linear motors 140 for moving the Y stage 120 in the Y-axis direction, and an X linear motor 150 for moving the X stage 130 in the X-axis direction.
The table 110 has an XY guide surface 110a which supports the lower surfaces of the Y stage 120 and the X stage 130 without contacting them through an air pad (not shown) or the like. A Y guide 111 rises from one of the ends in the X-axis direction of the table 110 in order to guide the Y stage 120 in the Y-axis direction. A guide surface 111a of the Y guide 111 and the Y stage 120 are kept separated and apart by means of an air pad (not shown) or the like. Driving both of the Y linear motors 140 causes the Y stage 120 to move above the XY guide surface 110a and along the Y guide 111.
The Y stage 120 is a long frame member comprising a pair of Y sliders 121 and a pair of X guides 122 disposed therebetween. The lower surfaces of the Y sliders 121 face the XY guide surface of the table 110, and are supported without contacting it by means of an air pad (not shown) or the like. One of the Y sliders 121 is longer than the other in the Y-axis direction, with a side surface 121a thereof facing the Y guide surface 111a of the Y guide 111 in order for the slider 121 to be guided without contacting the guide surface 111a through an air pad (not shown) or the like. Each Y slider 121 is integrally connected to a movable or moving element 141 of its associated linear motor 140 by means of a corresponding linking plate 123, and a stator 152 of the X linear motor 150 is fixed to the pair of X guides 122 formed integrally with both of the Y sliders 121.
The X stage 130 is a hollow frame member comprising a pair of top and bottom plates 131 and a pair of side plates 132 disposed at both ends thereof, with both of the X guides 122 of the Y stage 120 and the stator 152 of the X linear motor 150 extending through the hollow portion of the X stage 130. The bottom surface of the bottom plate 131 faces the XY guide surface 110a of the table 110, and is supported without contacting it through an air pad (not shown) or the like. The top surface of the top plate 131 is formed as a surface for holding a wafer (not shown) by attraction.
Inner surfaces 132a of the side plates 132 of the X stage 130 face X guide surfaces 122a corresponding to the outer surfaces of each of the X guides 122 of the Y stage 120 in order to be guided along the guide surfaces 122a without contacting them by means of an air pad (not shown) or the like.
The pair of Y linear motors 140 for moving the Y stage 120 in the Y-axis direction each comprises a moving element 141 and a stator 142. Each moving element 141 is integrally connected to an associated Y slider 121 of the Y stage 120 through its associated linking plate 123, while each stator 142 extends through the opening of its associated Y linear motor. Each stator 142 comprises a row of coils 142a arranged in the Y-axis direction and a support 142b supporting the row of coils 142a. On the other hand, each moving element 141 is a hollow frame member comprising a pair of opposing iron plates 141b for holding multi-polar magnets 141a and a pair of aluminum plates 141c affixed at both ends to its associated pair of iron plates 141b.
Successively switching the direction of current supplied to each of the flat coils of each row of coils 142a of each stator 142 of the Y linear motor 140 produces a thrust in the Y-axis direction in each of the movable elements, causing the Y stage 120 as well as the X stage 130 provided therearound to move in the Y-axis direction.
A movable element 151 of the X linear motor 150, which causes the X stage 130 to move along the X guides 122 of the Y stage 120, is a hollow frame member affixed to the bottom surface of the top plate 131 of the X stage 130. Like the moving element 141 of the Y linear motor 140, the movable element 151 comprises a pair of opposing iron plates for holding a multi-polar magnet 151a and a pair of aluminum plates affixed to both ends of each of the iron plates.
On the other hand, the stator 152 of the X linear motor 150 comprises a row of coils 152a arranged in the X-axis direction and a support 152b for supporting the row of coils 152a. When the direction of current supplied to each of the flat coils of the row of coils 152a is successively switched, each moving element 151 produces a thrust in the X-axis direction, causing the X stage 130 to move along the X guides 122 of the Y stage 120 in the X-axis direction.
The stator 142 of each Y linear motor 140 is integrally connected to the table 110 by fixing the supports 142b supporting their corresponding rows of coils 142a to both ends of the table 110.
However, in this conventional device, as mentioned above, the stator of each Y linear motor is integrally connected to the table so that the reaction force produced as a result of driving each Y linear motor is transmitted to the table. Since the table is supported in a flexible manner through the vibration removal device, the table rocks greatly when a reaction force is exerted thereon, thus changing the reference position of, for example, the laser interferometer which is used to measure the position of the XY stage, resulting in errors in measurements. Such a perturbation on the control system is a great obstacle to achieving quick positioning of the exposure apparatus and improving productivity. In addition, when the projection optical system supported by the table rocks, the exposure apparatus does not permit accurate transfer of the reticle pattern.
Since the stator of the X linear motor is integrally connected to the Y stage, the reaction forced produced in the stator due to the driving of the X linear motor is transmitted from a side surface of each Y slider of the Y stage to the Y guide formed integrally with the table, as a result of which the table rocks greatly, which perturbs the control system, as mentioned above.
In addition, when the X stage or the Y stage moves above the table, the position of the center of gravity of the whole XY stage changes, which tilts the table, thus resulting in such problems as changes in the reference position of the laser interferometer or the like, as mentioned above.